Groups of demonstrators began trickling into Martin Luther King Jr. Civic Center Park in downtown Berkeley on Thursday as police swarmed the city.

Among the activists at the park was Stewart Rhodes, founder of the citizen militia group known as theOath Keepers. Rhodes and his group had also gathered in Berkeley on April 15, when a planned “Patriots Day” rally erupted in clashes between pro-Trump demonstrators and counter-protesters.

"We are only here for self-defense," Rhodes said. His role, he said, was "to keep the hotheads in check."

Apr. 27, 2017, 12:44 p.m.

The city of Berkeley issued a warning to residents Thursday, urging them not to be "baited by provocateurs" and to "keep a distance from violence."

"Mass gatherings of any kind attract a broad variety of people and, inevitably, that means an array of different motives and intentions," read a statement posted by the city manager's office. "The overwhelming majority come with a peaceful purpose."

"However, in recent protests in Berkeley, we have seen a small portion who come seeking to hurt others or to destroy property. We have seen that individuals who come armed and armored use peaceful protesters as a cover for their violent actions."

Apr. 27, 2017, 12:43 p.m.

Berkeley officials warned students and residents to “keep a distance from violence” Thursday as police prepared for clashes between supporters and opponents of conservative commentator Ann Coulter.

Despite Coulter’s announcement a day earlier that she would not speak at UC Berkeley on Thursday, students and residents were told to expect a heavy police presence and asked to take precautions to remain safe.

By 10:30 a.m. Thursday, a police helicopter hovered over Martin Luther King Jr. Civic Center Park in downtown Berkeley as demonstrators in helmets and carrying flags on poles began to converge on the park.